Other Parts Discussed in Thread: SN74AHCT244-Q1, SN74AHCT244Q, SN74AHCT367
Hello, we are using SN74HCS367QPWRQ1 as our buffer driver fed from our MCU PWM outputs ( 3.3V ), we noticed that due to the internal clamp diode from input to Vcc, said input coming from our MCU PWM is enough to self bias the chip since Vcc can operate at as low as 2V. In our application we just shorted the enable pin to gnd and we are relying on the VCC to turn the device off to meet our safety interlock requirement but it was defeated because the internal clamp is self biased by our MCU via our input pulses. Is this expected?
Below is our implementation: Once the MCU starts to pulse, you can take off 5VS and the buffer will still work due to self biasing from internal clamp.
If we add reverse diode in series and add pull-up resistor at the input pin, will that cause any issue?
thanks,
Norman